For many years large machinery fitted with fuel tanks have been equipped with fast fill systems to enable rapid filling of large capacity fuel tanks. The existing fast fill fuel systems rely on an air vent that prevents air from escaping the fuel tank when the required level of fuel has been attained. This causes pressure in the fuel tank to increase to a level that automatically shuts-off a fuel supply nozzle.
A major concern of this system is that when the fuel level activates the shut-off for the fuel supply nozzle, the shut-off can be overridden and fuel can continue to be forced into the fuel tank above the normal level. This can cause the fuel tank to rupture from the high pressure attained when filling.
U.S. Pat. No. 6,311,723, (by the applicant), has addressed this problem by devising a flow control valve assembly that prevents the build up of pressure within the fuel tank during and after filling. The flow control valve assembly also prevents the supply fuel nozzle from being overridden thus preventing the possibility of overfilling. U.S. Pat. No. 6,311,723 is hereby incorporated by reference.
The control valve assembly of U.S. Pat. No. 6,311,723 uses a float valve to determine when the level of fuel in the fuel tank is at a desired level. When the desired level of fuel has been attained, the float valve is used to block the flow of fuel through a bleed pipe to stop the flow of fuel through a control valve. An open breather is provided within the fuel tank to allow gas to escape from the fuel tank during filling to prevent the fuel tank from rupturing.
The flow control valve assembly operates very effectively on machinery that is predominately stationary. However, when the control valve assembly is mounted to vehicles' fuel tanks, such as those located in trucks and excavators, some difficulties may be experienced during movement of the vehicle.
One problem that may be experienced is that the float valve may become broken. The float valve comprises a float that is mounted on a pivotally movable elongate arm. This arm can break due to the large forces that are exerted on the arm by the surging fuel caused by movement of the vehicle.
In the event that the control valve assembly fails, in this or any other manner, the fuel supply nozzle will continue to fill the tank and pass fuel through the open breather until the nozzle is shut-off manually. This may lead to many hundreds or even thousands of liters of fuel being wasted and the spilt fuel being disposed.
Another problem that occurs is fuel is passed through the open breather during movement of the vehicle. Fuel surges cause fuel to flow through the open breather and escape the fuel tank. Again, this wastes fuel and is environmentally unfriendly. Further, the spilt fuel also creates a fire hazard.